THE CORK STOPPER FOR SPARKLING WINE

User guide, a useful text for both professionals and to any people interested in the world of wine.

Sparkling Wine Handbook

The guide for the correct use of the cork stopper for sparkling wine has been published by FederlegnoArredo. It’s a useful text, both for professionals and for all the wine lovers, who, thanks to this handbook, will be able to know every detail of the basic bottling process.

To achieve and maintain the levels of excellence of our sparkling wines, a quality product is requested, but, consequently, it’s necessary to safeguard the wine’s aromas with a correct bottling and corking. Even a single defect in any of these elements could seriously compromise the behaviour of the sparkling wine in the bottle, nullifying the wise work of the winemaker. The following are some excerpts from this precious handbook; if you want to read it in its full version, please visit the website www.federlegnoarredo.it.

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THE MAIN VARIABLES TO BE TAKEN INTO CONSIDERATION

  • Sparkling process and awareness of the internal overpressure
  • Identification of the right type of sparkling cork stopper (classic cork stopper with washers, micro-agglomerated cork stopper with or without expanded microspheres) according to the wine that has to be bottled
  • Use of the cork stopper with the right diameter for the selected bottle
  • Adjustment of the right corking depth to avoid pressure loss of the wine or difficulty in extracting the cork itself

BOTTLING LINES
PRECAUTIONS AND WARNINGS

In specific T-Cork capper machines, the jaws must be possibly conical or truncated-cone and must be kept in perfect conditions of hygiene and integrity. The support and sliding surfaces must be intact, while the surfaces in contact with the cork stopper don’t have to be worn out, with smooth surfaces, free of rifling and chipping, even if of modest entity. Besides this, we the use of jaws requiring a limited lubrication is recommended to reduce the risk of contaminating T-Corks and bottles. With the appropriate devices provided by the manufacturer, it is necessary to check the final closing diameter, which must remain within values ​​between 15 and 16 mm.

Another important control must be carried out on the area of ​​support of the bottle mouthfinish to the plugs, which must be perfectly flat to allow the cylinder compensation spring to release the stress on the entire surface of the mouthfinish itself. Stress concentration gradients would be dangerous and critical and could generate glass microcracks. Further controls must be performed on the return springs for the reopening of the jaws, which must not show yielding, breakage or loss of elasticity.

Bottling Precautions

WIREHOODING OPERATIONS
Cork stopper inserted in the bottle before and after the wire-hooding process.   


WIREHOODING OPERATIONS

Immediately following the corking, if inserted correctly, the cork stopper must be perfectly vertical, in line with the bottle and with the leading edge of the lower part not chipped. The few seconds that elapse between corking and wire-hooding (recovering pause) are normally sufficient for the elastic recovery of the cork stopper, so that the part introduced into the bottleneck can begin to settle down and exert sufficient radial force to counteract the further sinking during wire-hooding. In the wire-hooding operation, the elements to be checked are:

  • vertical position of the cork stopper
  • constancy and suitability of its protrusion from the mouthfinish
  • alignment of the bottle
  • correct positioning of the cage
The wire-hooding operation causes a further sinking of the cork stopper up to 2 mm.

The further sinking of the cork stopper into the bottleneck, following the wire-hooding, depends on several parameters.
Those who tend to oppose, without being able to cancel it, are:

  • sthe corking machine has weakly introduced the cork stopper
  • excessive softness of the agglomerate, due to: low initial density, high percentage of humidity, too high cork stopper temperature
  • a too high cork stopper temperature could adversely affect the action of the lubricant
  • use of corking machines with conical jaws (positive fact, but it is necessary to take it into consideration)
  • jaws of the corking machine that excessively tighten the cork stopper
  • excessive duration of the recovering pause
  • slow increase in the pressure exerted by the wirehood put on the cork stopper (low production rate)
  • poor or deteriorated cork stopper coating, due to mechanical rubbing which can damage the coating layer
  • wrong size of the wirehood (too big)

The parameters which, on the other hand, tend to accentuate the further introduction of the cork stopper during the wire-hooding process, are exactly opposite to those listed above.

WIREHOODING OPERATIONS
Corking machine scheme with highlighting of the main parts.  

Go to the FederlegnoArredo sparkling wine corking manual page!

Visit the FederlegnoArredo website to read the complete manual, with all the precious case studies and the complete doctrine.
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